Hip joint contact forces increase in response to greater body-borne loads and faster walking speeds

Soldiers perform physically demanding tasks that predispose them to an elevated risk of musculoskeletal injury (MSKI). Understanding joint loading during commonly performed tasks, e.g., load carriage, may improve MSKI prevention efforts, yet current research is limited. Using EMG-informed neuromusculoskeletal (NMSK) models, we analyzed hip contact forces (HCF) from 20 soldier participants as they carried two different loads and walked at two different speeds. Increases in HCF were observed from both increases in carried load and walking speed, with HCF magnitudes approaching values observed during running. Importantly, muscles accounted for >50% of the total HCF and this contribution remained consistent with increasing task demands. Thus, our results suggest the effectiveness of injury prevention strategies should be analyzed using NMSK modeling approaches that incorporate estimates of muscle forces.